Radiation therapy or radiotherapy (RT) is a common curative procedure to treat cancer. The goal of the radiotherapy process is to expose the tumor to a sufficient dose of radiation so as to eradicate all cancer cells. The radiation dose is often close to the tolerance level of the normal body tissues. Therefore, it is necessary to determine the dosage levels in different parts of the irradiated body with high accuracy and precision.
Recent advances in radiological and biological imaging have improved cancer diagnosis and treatment. For radiation therapy, these advances make it possible to accurately delineate a tumor and radioresistant subvolumes inside a tumor. Consequently, complex and heterogeneous dose deliveries are often required. Modern radiotherapy techniques, such as Intensity Modulated Radiotherapy (IMRT), Volumetric Arc Therapy (VMAT), Stereotactic Radiosurgery/Radiotherapy (SRS/SRT), and Proton Therapy (PT), make it possible to implement such complex dose patterns.
As radiation therapy becomes ever more customizable to each individual patient, the complexities of the supporting treatment planning system (TPS) and the dose delivery system increase. This, in turn, necessitates an improvement in quality assurance (QA) methods used to verify the performance of the systems and to implement reliable pretreatment plan verification (PTPV) in clinical practice.
Therefore these complex radiotherapy procedures require sophisticated treatment planning, optimization of the radiation field, and verification of the delivery of the planned dose before the patient is subjected to radiotherapy. It is desirable to have the ability to measure the effects of the planned treatment fields with high accuracy and sensitivity in a three-dimensional volume of clinically relevant dimensions.